International standards which determine the purposes and ways of treatment of overhead bytes in the above-mentioned hierarchies do not go into details how the treatment should be performed in practice. Though, the requirements which are imposed by the standards to the monitoring of data streams (and connected with handling overhead information) cannot be satisfied without specific technologic developments, especially with respect to high order data streams having high bit rates. The relevant ITU-T Standard Recommendations G.707 (03/96) and G.783 (04/97) concerning SDH transmission hierarchy state how specific overhead bytes must be processed (for example, the handling of the first overhead byte J1 in the SDH standard frame: S. 9.3.1.1.in G.707 and 2.2.2.4 in G.783), but no solutions are proposed for implementing the procedure in any particular SDH data stream.
U.S. Pat. Nos. 5,465,252, and 5,600,648 concern handling SDH-SONET overheads and even specific bytes of such overheads, but do not describe rapid and economic ways of handling overheads of high order data streams.